1. Introduction
The previous research results indicated that humic substabces extracted from some compost materials were effectively and more rapidly improved soil chemical properties of marginal or
acid soils. It could decrease exchangeable Al and increased soil P availability through chelating process Winarso, et al, 2009a; 2010, therefore it could be an alternative to cope with problems
of marginally acid soils in Indonesia, which covered almost 102.8 million ha Puslitbangtanak, 2006. On the other hand, intensive agricultural lands were under harmful condition, due to high
content of high heavy metals. Wang 2006, stated that more than 10 of cultivated lands were contaminated with Cd, As, Cr, and Pb, which caused production lost more than 10 million tons,
and more than 12 million tons agriculture product per year became hazardous, which also caused economical lost at least 3 billion US dollars per year.
Heavy metals accumulation varied along with plant species, and generally higher on dicotyedoneael compared to monocotyledoneae plants Taub and Goldberg, 1996. While, on
the other hand, the potential agriculturalorganical waste, especially from palm oil was very abundant, approximately 6 million tons empty bunches in 2004 23 of total, excluding of wet
decanter solid 4, stem 6.5, fiber 13.0, and liquid waste 50. Based on the data released by Ditjenbun 2006, within the last 20 years, the addition of Palm Oil Estate areas
reached 5 million hectares, or increased by 837.
Up to nowadays, the utilization of organic waste for soil was just as composting, without any added values, therefore its commercial value was low. Increasing commercial value of
compost by extracting it to produce humic substabces was a very promising practice. The humic substances extracted from compost could utilized as the raw material of
biofertilizer and environmentally friendly bioremediation for heavy metals. In addition, humic substances have superior characteristics compared to that derived from mining Leonardit which
has been marketed commercially, especially abroad Winarso, et al., 2009b. Humic substances originated from mining contained very high Na, approximately 5., while
Na is generally needed by plants in very small amount. In fact, if Na is continuously added to soil, would cause soil compacted and dispersed when wet, and became easily eroded.
The mass and cheap production of humic substances usually would harvest low concentration, and its characteristic was determined by the quality of its raw materials. Therefore, some efforts
should be applied to activate its functional groups, such as through pH manipulation and adding synthetic organic substances rich in functional groups. In addition, enriching humic substances
with nutrients is very useful and beneficial to improve its functions and purposes as soil conditioner, fertilizers, and as heavy metals bioremediation. The chelating capability of humic
substances could improve their main function as bioremediation for heavy metal or other soil- environment pollutants
The aim of this research was to evaluate the effectiveness and the capability of humic substance extracted from Palm Oil bunches waste in improving cucumber or other plants
production and in reducing soil Cu heavy metals content.
2. Materials and methods
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